The use of gold plated stents is known in the art and is disclosed in a number of patents and patent applications including U.S. Pat. No. 5,824,045, U.S. Pat. No. 6,099,561 and copending and commonly assigned U.S. application Ser. No. 09/697634 filed Oct. 26, 2000. Gold plating increases the radiopacity of the stent, a feature that has proven useful for imaging purposes.
Over time, stents that have been implanted in the body tend, whether gold plated or otherwise, to have proteins adsorbed thereto which increases the likelihood of restenosis. While numerous surface modification treatments to achieve desired surface properties are known for stents, there remains a need for treatment processes for modifying the surface properties of stents having a surface of gold or other noble metals.
For the purposes of this disclosure, the term noble metal shall refer to a metal of the group Ruthenium (Ru), Rhodium (Rd), Palladium (Pd), Osmium (Os), Iridium (Ir), Platinum (Pt), Silver (Ag), and Gold (Au).
All U.S. patents and applications all other published documents mentioned anywhere in this application are incorporated herein by reference in their entirety.
The abstract provided herewith is intended to comply with 37 CFR 1.72 and is not intended to be used in determining the scope of the claimed invention.
Without limiting the scope of the invention in anyway, the invention is briefly summarized in some of its aspects below.
The instant invention is directed in at least some of its embodiments to coated stents. Other embodiments of the invention include methods of coating stents.
In one embodiment, the invention is directed to a stent having a body and a surface, at least a portion of the surface comprising a metal with a coating on the metal. The coating is selected from the group consisting of thiols and disulfides and combinations thereof. The thiols are of the form Rxe2x80x94SH and the disulfides are of the form Rxe2x80x94Sxe2x80x94Sxe2x80x94Rxe2x80x3 where R and Rxe2x80x3 are alkyl groups. Suitably, R has at least 4 carbons. Desirably, R has from 12 carbons to 32 carbons. More desirably R has from 12 to 24 carbons. Suitably, Rxe2x80x3 has at least 4 carbons. Desirably, Rxe2x80x3 has from 12 carbons to 32 carbons. More desirably Rxe2x80x3 has from 12 to 24 carbons. Only a portion of the surface may be metal or, more desirably, the entirety of the surface may comprise the metal. The metal desirably is selected from the group consisting of noble metals, copper and silver and combinations thereof. Where the metal is gold, the gold may be coated on the body of the stent via plating or any other technique. Desirably, the thiol and/or disulfide coating is substantially one monolayer thick.
The invention is also directed to a method of preparing a stent comprising the steps of providing a stent having a surface at least a portion of which is metal and coating the metal surface with a coating moiety selected from the group consisting of thiols and disulfides and combinations thereof. The thiols are of the form Rxe2x80x94SH and the disulfides are of the form Rxe2x80x94Sxe2x80x94Sxe2x80x94Rxe2x80x3 where R is an alkyl group and Rxe2x80x3 is an alkyl group. Suitably, R has at least 4 carbons. Desirably, R has from 12 carbons to 32 carbons. More desirably R has from 12 to 24 carbons. Suitably, Rxe2x80x3 has at least 4 carbons. Desirably, Rxe2x80x3 has from 12 carbons to 32 carbons. More desirably Rxe2x80x3 has from 12 to 24 carbons. Desirably, the entire surface of the stent is coated in the coating step. Also desirably, the metal is selected from the group consisting of noble metals, copper and silver. More desirably, the metal is gold. In accordance with the inventive method, the coating moiety may be disposed in a solvent such as methanol, ethanol, isopropanol and combinations thereof and the stent placed in the solvent. The coating may be provided via other techniques as well including spraying the coating on the metal surface of the stent. Desirably, the coating is substantially one monolayer thick.
The invention is also directed to a stent at least a portion of which has a substantially monolayer thick coating of one or more members selected from the group consisting of thiols, disulfides, and combinations thereof. Desirably, at least a portion of the stent includes a layer of gold thereon, the monolayer coating disposed on the layer of gold. More desirably, the gold layer and monolayer coating extend over the entirety of the surface of the body portion of the stent.
A detailed description of the invention in its various embodiments is provided below.